Pop safety-valve



(No Model.)

R. F. PRATT.

POP SAFETY VALVE.

Patented Feb. 26, 1889.

PATENT Erica RONELLO F. PRATT, OF BOSTON, MASSACHUSETTS.

POP SAFETY-VALVE.

SPECIFICATION forming part of Letters Patent No. 398,445, dated February26, 1889.

Application led April 10, 1888.

.To @ZZ whom it may concern.;

Be it known that I, RONELLO F. PRATT, a citizen of the United States,residing at Boston, in the 'countyof Suffolk and State of Massachusetts,have invented a new and useful Improvement in Pop Safety-Valves, ofwhich the following is a specification.

In what are known as pop safetyvalves now in use various means have beenadoptedto adjust the spring so that the valve will open at agivenpressure; but in all cases screws have had to be .adjusted withoutany indication as to the pressure at which the .valve will open, and itis impossible to adjust the valve as required without the employment ofa pressure-gage. It also requires a person of considerable skill toadjust them so that the valve will work properly.

The object ot my invention is to overcome these difficulties; and theinvention consists in constructing a valve with a graduated scale, sothat any ordinary mechanic can adjust it to open at the desired pressureby turning a single nut.

The invention further .consists in so arranging the spring within thebody of the valve as to be free from contactV with the steam, therebypreserving its elasticity.

Referring to the accompanying drawings, Figure l represents an elevationof a pop safety-valve embodying my invention. Fig. 2 is a verticalsection of the same. Fig. 3 is a horizontal section taken through theline ai :c of Fig. 2. Fig. shows a modification.

A is the outer casing or body of the valve, provided at its lower endwith an inwardlyprojecting screw-threaded flange, a, the upper end ofthe casing being closed with the eX- ception of a small screw-threadedopening to receive a nut, l, and on one side of the body A is provided ascrew-threaded opening, A', through which the steam escapes when thevalve is opened.

O is a cap or cover provided with two upwardly-projecting rims, c c',the inner one being provided on its outside with a screwthread that fitsin the thread on the iiange a, and this rim also forms a seat for thevalve. The outer rim, c', comes outside the casing A, and is employed toindicate the pressure to Serial No. 270,213. (No model.)

which the spring is set by means of a graduated scale on the outside ofthe body A, as shown in Fig. l. The lower end of this Cap isscrew-threaded to connect it with the boiler.

D is the valve, which rests upon a seat formed in the upper end of therim c, and is provided near its lower end with a flange, d, upon whichrests one end or a strong spiral spring, F., the other end of the springbearing against the upper end of the body A, as 6o working order theouter end of the lever F 7o can be drawn down, thereby raising the valveott its seat. Its operation is as follows:

The valve, by means of the cap C, being connected to the steam pipe orboiler, and the tension of the spring E having been properly adjusted,the steam passes up against the top of the valve-body, and when thelimit ot' pressure of steam is exceeded the valve D opens and allows thesteam to pass into the space between the valve-body and the body A and8o up and out of the opening Athereby producing instant relief, and assoon as the pressure is reduced the valve again closes.

Should it be desired to alter the pressure at which the valve will open,all that has to be done is to turn the body A one way or the other bymeans of the nut a2 formed on the top thereof, until the upper edge ofthe rim c is on a line with the required mark in the grad* uated scaleon the outside of the body A. 9o

The cap C maybe held by means of a wrench or Spanner placed on the nutor square portion c2, so as not to turn when the body 'A is moved.'

In Fig. 4 I have shown the cap O secured 95 to the body A by means of acoupling similar to the ordinary union pipe-coupler. In this case thecap O passes freely through the flange a of the body A, and is providedwith a iiange,

c3, and held to the body A by a collar, C,pro roo This lever presses out65 vided with an inwardly-projeeting flange and screwed onto the outsideof the body A, as shown.

Although I have described the Valve as being employed for steam, it isequally applicable to any place when. the relief' of pressure isrequired, and particularly adapted for feedwater heaters, so as tomaintain the pressure in the heater at or about that of the boiler, theValve being,l easily and quick] y adj usi ed to the required pressure.

Vhat l claim as my invention is` l. In a pop safety-valve, the body A,provided at its lower end with an inwardly-projeeting,` flange, a, capor cover C, provided with upward lyeprojeeting rims c c', in combinationwith the valve l) and spring E, substantially as and for the purposesset forth.

2. In a pop safety-valve, a Valve, l), eonsisting` of a hollow Cylinderclosed at the top and provided with a flange, d, in Combination with thespring,` E and body A, the spring being placed between the flange d andtop of body A, whereby the valve is held to its seat in the cap C,substantially as and for the purposes set forth.

3. In a pop safety-Valve, the body A, provided on .its outside with agraduated scale,

in Combination with a cap or cover, C, provided with two upwardly-irirojectin rims, e c', so that the body A is connected by ascrewthread to the rim c, while the rim c acts as a pointer to indicatethe pressure at which the Valve will blow ol'f, substantially as shownand described.

4:. A pop safety-valve eo'nsistinl of the following1 elements: an outercasing,` provided on 'its outer side with a graduated scale and at itslower end with an inward ly-progeetingl serew threaded flange, a cap orCover provided with a steamdnlet and two upwardly-projecting rims, theinner one being screwihreaded to connect with the casing and the outerone serving' as a pointer on the graduated scale, a hollow cylindricalValve provided on its outside with a flange near its lower end, and

a spiral spring, all arranged and operating substantially as set forth.

In testimony whereof l have sign ed my name to this specification inthepresence of two subseribing` witnesses.

RONELLO F. PRATT.

Titnessesr y l CHAS. STEERE, E. PLANTA.

